CA1270713A - Sheet containing a plurality of surgical needles - Google Patents

Abstract

ABSTRACT
A unitary metal sheet formed from a single sheet of metal containing a plurality of surgical needles.
Each needle has a pointed end and a suture attachment end. The needles are arranged in spaced relation-ship along a plurality of continuous rows and are attached at the suture attachment end by breakable connections to base rows that extend substantially across the width of the sheet.

Description

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This is a division of patent application Serial No. ~97,637 filed December 13, 1985 The present invention relates -to a unitary me-tal sheet containing a plurality of surgical needles which are arranged in a spaced relationship along a plurality Of continuous rows and are at-tached at the suture attachment end by breakable connections.
Surgical needles are made, one at a time, by a multi-step process involving considerable time, labor, and precision machinery. A brief outline of a typical process for making surgical needles is the fo]lowing.
Stainless steel wire of the appropriate diameter is straightened and cut to the desired length to form a blank. One end of the blank is die-formed and/or ground to produce a cutting edge or point. The other end is either drilled to orm a hollow receptable for a surgical suture, or it is stamped to form a channel fors~waging the suture. The point is sharpened, and the needle is bent. As a rule, the final steps are a heat treatment to temper the needle, that is ! to increase the hardness without imparting brittleness, and a polishing process. After this, sutures are attached to the needles by any of several means. ~ne additional feature of the prior art process for making surgical needles is tha-t the shape o~ the needle is limited by what can be done to a piece of wire. ~s will be apparent below, this inventlon provides a process that can be used to make any shape that can be drawn in two dimensions.
The multi-s-tep process is acceptable for the production of relativel~ large surgical needles, but with the advent of microsurgery and the need for .

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ever smaller surgical needles, the process has proven to be quite inefficient for the production of small needles having diameters of, e.g., from one to three mils because of the large amount of skilled labor and precision machinery required in handling such small needles individually throughout the various steps of the process leading to attachment of sutures and final inspection.
This invention provides a process tha-t is parti-cularly well adapted to the efficient simultaneous production of large numbers of small size surgical needles.
According to a broad aspect of the present invention, there is provided a unitary metal sheet formed from a single sheet of metal containing a plurality of surgical needles. Each needles has a pointed end and a suture attachment end. The needles are arranged in spaced relationship along a plurality of continuous rows and are attached at the suture attachmen-t end by breakable connections to base rows that extend substantlally across the width of the sheet~

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~6)7~L~3 The Pr ior Art ~eath, in U.~. Patent No. 2,735,763, ~iscloses a photo-etching process for makinq small parts from a sheet of thin metal which will not withstand any mechanical working.

Jacks et al., in U.SO Patent No. 3,35R,363, discloses a photoetching process for making fuse elements.
Snyder, in U.S. Patent No. 3,816,273, discloses a photo-etching process for making wire.

Poler, in U.S. Patent No. 4,080t709, discloses a photo-etching process for making the mounting structure for an intra-ocular lens.

ninardo~ in ~.S. Patent No. 4,282,311, and James, in U.~. Patent No. 4,2~4,712, disclose a photoetching process for making flylea~s for video flisc styli.

nrief nescription ~

Fi~. 1 is a top plan view of a metal sheet containing a plurality of surgical needles produced by the process of the invention;

Fig. 2 i~ an enlargcment o a portion of the shee~ of Fig. 1;
Fig. 3 is an enlarged perspective view of a surgical needle made by the process of ~he invention;

Fig. 4 is a perspective view of the needle of Fig. 3 attached to a surgical suture;

.''" ' ' ~71)~ 3 Fig. 5 is an enlar~ed plan view of a photomask of the image of a single surgical nee~le that can be used in carrying out the process of the invention;

Fig. 6 is an enlarged plan view of a second photomask of the image of a single surgical needle that can be used in carrying out the process of the invention;

Fig. 7 is an enlarged view of a portion of ~ig. 5;
Fig. 8 is an enlarged perspective view of the suture attachment end of the needle of Fig. 3;

Fig. 9 is a cross-sectional view ~aken along line 9-9 of Fig. 8, and a~ditionally showlng a suture ~ttached to the needle;

Eig. lO is an enlarged view of a portion of Fig. 2;

Fig. ll is a cross-sectional elevation taken along line ll-ll of Fig. 10; an~

Eig. 12 is an enlargement of a portion of Fig. 5.

~ f the Invention The first step in the process of the invention is to coat at least one side of a metal sheet with a light sensitive photore6ist material. The metal sheet that is used can be selectefl so as to possess all o the strength, hardness, tuughness, and grain structure, in the sheet form that the metal will need in the form of a surgical needle. This is one advantage over the current multi-step process for producing surgical needles, in which one step is usually a 3~ heat treatment step to develop optimum properties. Any metal or allo~ that can be obtained in thin sheet form can ET~-643 '~: ' , ~, , .

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be used, provided that it has the re~uisite properties of strength, hardness, etc. ~or instance, a tensile strength of at lea~st ahout 300 ,oon psi, a Rockwell C hardness of at least 45, and ductility so that the needle can be bent up to about 90 and then straightened without breaking, are desirable. The metals that can be used include stainless steel, specifically, 3Z0 stainless steel and ~in 5 and ~,in 6 razor blade grade stainless steel, and molybdenum. Gin 6 stainless steel is preferred. The metal sheet will ln usually have a thickness of from about one to about ten mils.
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The photoresist compositions used are known in the art.
For instance, they are discussed in "Photo-Resist Mate-rials and Processes" by ~illiam DeForest, McGraw-~ill 1975, and a wide variety of photoreslst compositions are available commercially~ The metal sheet can be coated with the photoresist by any convenient method, such as flip coating, spraying, and the like. In a preferred aspect of the invention, both sides of the sheet are coated with the photoresist an~ the needle images are formed on both sides. (In any event, the second side must be coatecl with either a photoreslst or a protective coating.) In a typical coating process, the metal sheet is thorou~hly cleaned, rinsed, dipped in dilute aqueous acid, e.g., 10%
HCl, rinse~ again, dried, and then c~ated. Since the photoresist compositions are sensitive to light/ the coating should be carried out under "safe light" condi-tions, e.g., under yellow or orange light, or in the dark.
3n After coating, the coated metal sheet is baked at a moderately elevated temperature for a few minutes, e.g., at about ~n oc . for about ln minute5, to dry the coating After the coated sheet has cooled, it is then exposed to ET~-643 : '~ ", , : ~ . .
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light in the image of a plurality of surgical needles, shaped to compensate for lateral etching of metal during the etching step, a principle that is well understood in the art. This is done hy first covering the coated sheet with a negative or first photomask containing an image of the needles. An illustrative enlarged negative or first photomask of a single surgical needle is shown as 14 in Fig. 5 (it will be discussefl in more detail) below. In a preferred aspect of the invention, the coated reverse side of the metal sheet is then covered with a second photomask that is the mirror image of the first photomask 14 and in perfect register therewith, and then exposed to light. An illustrative enlarged second photomask of a single surgi-cal nee~le is shown as 16 in Fig. 6~ As will be explaine~
in more detail below, the said second photomask 1~ may differ in certain details from the said first photomask 14. The light source used to expose the photoresist is rich in ultraviolet ra~iation. A carbon-arc light is preferred, but ~ercury-vapor lamps o~ ultraviolet rich fluorescent lights may also ~e usefl. Typical exposure times are within the range of a few seconds to several minutes, ~epen~ing u~on the nature and power o~ the light source, the distance of the light from the photoresist, and the sensitivity of the photoresist. The lnstruction~
of the manu~acturer of the photoresist~should be followed in this respect.

After exposure, the photoresist is rinsed in a suitable commercially available "developer" formulate~ for the particular photoresist being used, to remove the unexposed photoresist. After Yinsing~ the sheet with the photoresist coating in the form o~ surgical neeflles may be ~aked at, e.g., 120 to ~fiOC. for 5 to 1~ minutes to fu~ther harden the remaining photoresist coating. The next step is to etch away the unwant d metal in an etching solution. Typical etching solutions include 36- to 42-ETI~-643 , ' , , ., ~'7C~7~3 degrees Baum~ a~ueous ferric chloride, an a~eous mixture of ferric chlori~e and HCl, or a mixture of aqueous hydrochloric acid and nitric acid, or the like. ~uch etching so~utions are known in the art, as is their use in a photoetching process. After the etching step, there remains the desired surgical needles, which are removed from the etching solution, washed, and dried. The developed and hardened photoresist is then removed by dissolving away with a suitable co~mercially available stripper forMulated for the photoresist being used. A
detailed ~iscussion of the application of the above process to a specific surgical needle design follows~

A surgical needle to be produced hy the process of the invention is shown as 12 in Fig. 3~ The needle inclu~es a shank 18, a point 20, and a suture attachment end 22. In this Aesign, the suture attachment en~ 2 includes a channel 24 ~y which a suture 26 may be attached, as is explained in more detail below. The first step in using the process of the invention to produce this needle 12 is to make a precision black ~rawing of the neeflle 12 several hundre~ times larger than the re~uired finished siæe.
This drawing is then optically reduced to the required size, and an exposure is ma~e near the corner of a sheet of high resolution film. The film is moved laterally by a precision stepping device and a second exposure is made.
This is repeated until a row of exposures across the film is completed. The stepping device moves the film upward by one rowls wi~th, an~ a second row of exposures is made~
This process i~ repeatefl until the entire film area ls coverefl. The film is then developed to produce a negative or photomask of the images of the needles.

Fig. 1 shows a sheet ~8 containing a plurali~y of surgical needles 1~ attached at their suture attachmen~ ends ?.2 to - continuous base rows 30 that extend the width of the sheet ET~-643 ...

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2R. An enlarge~ent of a portion of the ~heet 2~ showing one needle 12 is shown in Fig. 2. An enlargement of a ~hotomask 14 corresponding to this needle 12 is shown in ~ig. 5. The di~ensions of the image 12a of the needle in the photomask are ~odified to allow for lateral etching of the metal during the etching step. The photomask image of a particular part will be referred to by the same reference number, with the addition of an "a" to the num~er. Thus, the photomask image of the needle 12 is 1~ referred to by the reference number 12a.

As a first approximation, the metal will be etched lat~rally about the same distance as vertically. Thus, ln the preferred situation wherein the ~etal sheet is etched 1~ from both sides, lateral undercutting equal to approxi-mately one-half the thickness of the sheet should be allowed for in the photomask. The image 2na of the nee~le's point in the photomask preferahly ~oes not come to a point, but rather is preferably hluntefl as is shown in Fig. 5. Lateral etching will cause a point to be formed. This is shown schematically in Fig. 7~ which is an enlar~e~ent of the image 20a of the needle's point.
The arrows show the directlon o~ lateral etching of the metal so that, after the etchin~ step, the point of the

2~ nee~le will have the configuration shown in dashed lines in Fig. 7. (If the needle's point were pointed in the photomask, aEter etching, the point would probably be rounfleA rather than sharply pointed, as a resul~ o~ the lateral etching.)

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For ease of handling the needles produced hy the process of the invention, it i5 preferred to prodllce the needles such that they are attached by a breaka~le connection to the metal sheet ~rom which they are etched. ~y so doing, 3~ the needles can ~e kept separated and in order until they are ready for ~urther processing. One way to do this is :, . . . .. ~ ~

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707~3 g illustrated in the drawings (see, especially, Figs. 1, ~, 5, and 6). The sheet 28 shown in Fig. 1 has the needles 12 attached to base rows 30 that extend all the way across-the sheet. To assist in the removal of the individual needles 12 from the base rows 30, a transverse groove 32 may be made at the point of attachment of the needle 1~. to the base row 3~ See Figs. 10, 11 and 1~.) In the photomask 14, the groove 32 is provided for by a transverse line ~2a, in one of the two photomasks only, at the point of attach~ent to the base row 30a.

Reerring now to ~igs, 5, 6, ~, and ~, the suture attach-ment en~ 2~ includes a channel 24 for use in attaching the needle to a suture 2~. In the embodiment shown, the channel ~4 is a bilevel channel in which the first half 34 of the channel is offset longitudinally from the second half 36, as is shown clearly in Figs. 8 and 9. The two halves of the channel are etched equally from both sides of the metal sheet so that each has a depth of about one half the thickness of the sheet. Where the two halves 34, 36 overlap, a hole 3~ is pro~uced so that the two halves 34, 36 com~unicate with each other. A suture 26 is atkachefl by ~illing both halves 34, 3h with an adheslve material (not shown) such as an epoxy glue while the ~5 second half 36 is lying on a flat surface, and then inserting the end of a suture 2fi through the hole 38 hetween the two halves, 34, 36 as ls shown in ~ig. 9. The epoxy resin is kardened at roo~ temperature, and then given a final cure in an oven at moderately elevated temperatures, such as 40~ to 6noc. The photomask images 34a, 36a, of the two halves of the channel are thin lines, as is shown in ~igs. 5 an~ 6, to allow for the lateral etching that will occur during the etching process. The "bilevel" channel desc~ibed here has several advantageous properties. ~irst, it serves to hold the suture securely in place while the adhesive sets, and, second, it helps to ., .: : , :
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-ln-prevent the suture from being pulled out of the channel hy a lateral force.

The needles 12 may be detached from the sheet 28 before attaching to a suture 26. This can be ~one by grasping a single needle 12 with forceps and flexing it at the break-off groove 32. Alternatively, all neeflles in a single row can be detached simultaneously by cutting both ends of the base row 3n, removing it from the sheet 28, and then pressing the row of nee~les lightly on to an a~hesive surface. Flexing the base row 3~ upwards will cause it to break off at the break-off grooves 32, leaving the neeAles precisely spaced and securely held on the adhesive surface in an ideal position for suture attachment.
After the etching step and after removal of the hardened photosistj if des-red, entire sheets of neeflles may be electropolished using conventional electropolishing methods to smooth off rough edges, polish the surfaces, 2n and improve the shape of the needle points hy reducing or eliminating undesirahle projections, and hy sharpening the edge. This is another advanta~e of the invention, since hundreds, and perhaps thousands, of needles can he electropoli~hed simultaneously in a Eew minutes.
A typical electropolishing bath is an a~ueous sul~uric, phosphoric, and glycolic aci~ bath. Polishing times of about 30 seconds at ten volts and ~noc. are typical.

The invention has heen described and claimed in terms o~ a dry positive photoresist technique, that is, the hardened photoresist on the metal sheet is in the image of the part - that is to be made. It is theoretically possible to use a wet photoresist or a negative phokoresist technique in carrying out the process of the invention, although to do so would be awkward and uneconomical.

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Claims (2)

The embodiments of the invention in which an exclusive property or privilege is claimed are defined as follows:

1. A unitary metal sheet formed from a single sheet of metal containing a plurality of surgical needles, each needle having a pointed end and a suture attach-ment end, wherein the needles are arranged in a spaced relationship along a plurality of continuous rows, and wherein said needles are attached at said suture attachment end by breakable connections to base rows that extend substantially across the width of said sheet.

2. The metal sheet of claim 1 wherein the suture attachment end of said needle includes a bilevel channel including a channel on opposite sides of said needle, wherein the said two channels are offset longitudinally by overlap, and wherein the two channels communicate with each other at the overlap.